In this article, CAFRE’s Nigel Gould discusses fluke control in sheep.
You should assess the threat of liver fluke in your flock and develop an appropriate treatment strategy with your vet.
Liver fluke requires an intermediary host, the mud snail, which is generally more prevalent in wetter areas.
Higher levels of rainfall throughout the year and mild winters provide an ideal environment for the mud snail to thrive.
Consider the incidences of liver fluke on your farm in previous years and the type of ground the flock are grazing.
If you send lambs or cull ewes for slaughter, ask plants to check livers for fluke.
You could use faecal sampling. However, the test only detects fluke eggs, indicating the presence of adult fluke.
It takes ten to twelve weeks for fluke to mature and before eggs are laid. Considerable damage can occur by the immature fluke migrating to the liver.
Two forms
There are two forms of liver fluke: acute and chronic.
Acute fluke affects sheep, mainly in autumn, whilst the chronic form impacts both sheep and cattle.
The migration of a large number of immature flukes to the liver causes acute liver fluke. It can be linked to a period of high summer rainfall.
The chronic form can persist through the year, but mainly occurs in winter and spring.
It can result in reduced thrive, and in some cases, animals show swelling under the jaw.
Fluke control in sheep: Products
Triclabendazole is the only flukicide group that targets the early immature stages of liver fluke.
However, there have been cases of defence to this group, which is a cause for concern.
Therefore, it is important to protect the efficacy of this flukicide. This can be achieved through a farm-specific targeted fluke treatment strategy, including using other flukicide groups.
For example, if sheep are being treated at least four weeks after housing, there is no need to use a triclabendazole product.
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